The present disclosure relates generally to calibrating a pressure sensing device that can be used within the human body.
Pressure sensors suitable for insertion into the human body have been available for many years. These devices have been reduced in size such that they can now be placed in many different areas of the body including insertion into the vasculature. In one particular application, a miniature pressure sensor is mounted on a guidewire. The guidewire may be inserted into an artery and advanced into the coronary arteries supplying blood to the heart muscle. The guidewire can be positioned adjacent a stenosis to provide pressure information both proximal and distal to the lesion.
Due to their small size and manufacturing considerations, miniature pressure sensors have a significant degree of variability in their signal output. Such variability can include differing pressure sensitivities, zero pressure offsets, and temperature coefficients. To account for these variations, pressure sensors are typically calibrated as part of the manufacturing process and the calibration coefficients derived from that process are associated with the particular device.
In the intravascular pressure sensing system 10 shown in FIG. 1A, a guide wire 12 with a distal pressure sensor 14 is interconnected with the console via a series of connections and cables. The wire 12 is joined to the rotary connector cable 18 by a rotary connection assembly 16. On the proximal end of rotary cable 18 is a connection housing 20 that is joined to a patient interface module (PIM). The PIM is then connected to the console 50 via cable 24 through connection 26 joined to console connector 27. The connection housing 20 includes both the wires 30 leading to the pressure sensor 14 as well as a series of resistors 32. The resistors are selected during the calibration process at the manufacturing facility to encode the sensor calibration coefficients. When connected, the PIM 22 measures the resistor values to determine the calibration coefficients and then processes the raw sensor signals received on wires 30 accordingly. The PIM 22 then sends the calibrated signals through cable 24 on to the console for further processing.
In another form shown in FIG. 1B, the resistors disposed in the connector 20 have been replaced with an EEPROM 40. The cable is directly connected to the console 50. In this version the EEPROM is programmed with the calibration coefficients.
There remains a need for an improved system of calibrating pressure sensors and providing calibrated data signals to the processing console 50.